@book{21501,
	author = {Benson, Carol B.},
	title = {Ultrasonography in obstetrics and gynecology :},
	publisher = {Thieme,},
	year = {c2008.},
	address = {New York :},
	edition = {2nd ed.},
	url = {http://www.loc.gov/catdir/toc/ecip0715/2007015102.html}
}